Gracilis is one of the medial thigh muscles. It originates from the body and inferior ramus of the pubis. As a long, slender strap, it passes distally on the medial aspect of the thigh. It inserts into the anteromedial surface of the superior part of the tibia. At its insertion it lies posterior to the insertion of sartorius but anterior to that of semitendinosus.
Gracilis is innervated by the anterior division of the obturator nerve (L2,L3).
Crossing both hip joint and knee joint, it acts to weakly:
- adduct the thigh at the hip joint
- flex the thigh at the hip joint
- medially rotate the knee when the latter is flexed
Gracilis tends to play a supplementary role in most of these movements and as such, it is readily used as substitute muscle at other sites.